Superabsorbent polymers (SAPs) are synthetic polymer materials having a capacity for absorbing 500 to 1000 times their own weight in moisture. Although developed for practical use in sanitary items such as disposable diapers for children, sanitary pads, etc., SAPs now find additional applications in a variety of fields including raw materials in soil conditioners for horticulture, water stopping agents for civil engineering and construction applications, sheets for raising seedlings, freshness preservatives for food distribution, goods for fomentation, and the like. In the synthesis of SAPs, water plays various roles, for example, as a polymerization medium, and to facilitate the dispersion of a cross-linking agent upon surface cross-linking. When absorbing water, however, SAPs increase in stickiness on the resin surface, and their particles undergo irreversible agglomeration. Because this viscosity increase and agglomeration brings about poor processability, such as a load increase, in the preparation and applied processes, the use of silica and organic solvents has been adapted to avoid the problem, but causes the SAPs to decrease in physical properties and productivity and thus to increase in production cost. Particularly, permeability, which is one of the main properties of SAPs for use in pulpless diapers, is degraded as the core-shell structure of SAPs is destroyed during the manufacture of the diapers. To prevent the degradation of such properties a novel approach to the surface crosslinking of SAPs is presented.